Surveyor asks for a lever type diesel shut off valve to replace the original gate valve outlet from tank, what thread or size is this valve. 81 Fulmar.
It's the same size and thread of my old Triumph fuel cock.I know because I use exactly the same on the Fulmar and the Triumph.From memory 1/2 inch? pipe thread.I can check and let you know.Trafalgar Yacht Services should carry them.They cost around 2£.
You will find that the gate type valve still works! What I did was leave the existing valve in place ( don't want to be fiddling around in that cramped area) then extend the diesel fuel pipe from the tank to the front of the engine, install a small valve designed for the purpose from ASAP followed by CAV type filter and then on back to the lift pump (the point where the fuel originally entered the engine.
This means that the valve and filter are both easily reached from the front of the engine box. I always turn mine off when leaving the boat.
Mine's an 82 Fulmar so you, like me , will have the very large engine casing therefore plenty of room for this.